1 //===--------- llvm/DataLayout.h - Data size & alignment info ---*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines layout properties related to datatype size/offset/alignment
11 // information. It uses lazy annotations to cache information about how
12 // structure types are laid out and used.
14 // This structure should be created once, filled in if the defaults are not
15 // correct and then passed around by const&. None of the members functions
16 // require modification to the object.
18 //===----------------------------------------------------------------------===//
20 #ifndef LLVM_IR_DATALAYOUT_H
21 #define LLVM_IR_DATALAYOUT_H
23 #include "llvm/ADT/DenseMap.h"
24 #include "llvm/ADT/SmallVector.h"
25 #include "llvm/IR/DerivedTypes.h"
26 #include "llvm/IR/Type.h"
27 #include "llvm/Pass.h"
28 #include "llvm/Support/DataTypes.h"
42 /// Enum used to categorize the alignment types stored by LayoutAlignElem
44 INVALID_ALIGN = 0, ///< An invalid alignment
45 INTEGER_ALIGN = 'i', ///< Integer type alignment
46 VECTOR_ALIGN = 'v', ///< Vector type alignment
47 FLOAT_ALIGN = 'f', ///< Floating point type alignment
48 AGGREGATE_ALIGN = 'a' ///< Aggregate alignment
51 /// Layout alignment element.
53 /// Stores the alignment data associated with a given alignment type (integer,
54 /// vector, float) and type bit width.
56 /// @note The unusual order of elements in the structure attempts to reduce
57 /// padding and make the structure slightly more cache friendly.
58 struct LayoutAlignElem {
59 unsigned AlignType : 8; ///< Alignment type (AlignTypeEnum)
60 unsigned TypeBitWidth : 24; ///< Type bit width
61 unsigned ABIAlign : 16; ///< ABI alignment for this type/bitw
62 unsigned PrefAlign : 16; ///< Pref. alignment for this type/bitw
65 static LayoutAlignElem get(AlignTypeEnum align_type, unsigned abi_align,
66 unsigned pref_align, uint32_t bit_width);
67 /// Equality predicate
68 bool operator==(const LayoutAlignElem &rhs) const;
71 /// Layout pointer alignment element.
73 /// Stores the alignment data associated with a given pointer and address space.
75 /// @note The unusual order of elements in the structure attempts to reduce
76 /// padding and make the structure slightly more cache friendly.
77 struct PointerAlignElem {
78 unsigned ABIAlign; ///< ABI alignment for this type/bitw
79 unsigned PrefAlign; ///< Pref. alignment for this type/bitw
80 uint32_t TypeByteWidth; ///< Type byte width
81 uint32_t AddressSpace; ///< Address space for the pointer type
84 static PointerAlignElem get(uint32_t AddressSpace, unsigned ABIAlign,
85 unsigned PrefAlign, uint32_t TypeByteWidth);
86 /// Equality predicate
87 bool operator==(const PointerAlignElem &rhs) const;
91 /// DataLayout - This class holds a parsed version of the target data layout
92 /// string in a module and provides methods for querying it. The target data
93 /// layout string is specified *by the target* - a frontend generating LLVM IR
94 /// is required to generate the right target data for the target being codegen'd
95 /// to. If some measure of portability is desired, an empty string may be
96 /// specified in the module.
97 class DataLayout : public ImmutablePass {
99 bool LittleEndian; ///< Defaults to false
100 unsigned StackNaturalAlign; ///< Stack natural alignment
102 SmallVector<unsigned char, 8> LegalIntWidths; ///< Legal Integers.
104 /// Alignments - Where the primitive type alignment data is stored.
107 /// @note Could support multiple size pointer alignments, e.g., 32-bit
108 /// pointers vs. 64-bit pointers by extending LayoutAlignment, but for now,
110 SmallVector<LayoutAlignElem, 16> Alignments;
111 DenseMap<unsigned, PointerAlignElem> Pointers;
113 /// InvalidAlignmentElem - This member is a signal that a requested alignment
114 /// type and bit width were not found in the SmallVector.
115 static const LayoutAlignElem InvalidAlignmentElem;
117 /// InvalidPointerElem - This member is a signal that a requested pointer
118 /// type and bit width were not found in the DenseSet.
119 static const PointerAlignElem InvalidPointerElem;
121 // The StructType -> StructLayout map.
122 mutable void *LayoutMap;
124 //! Set/initialize target alignments
125 void setAlignment(AlignTypeEnum align_type, unsigned abi_align,
126 unsigned pref_align, uint32_t bit_width);
127 unsigned getAlignmentInfo(AlignTypeEnum align_type, uint32_t bit_width,
128 bool ABIAlign, Type *Ty) const;
130 //! Set/initialize pointer alignments
131 void setPointerAlignment(uint32_t AddrSpace, unsigned ABIAlign,
132 unsigned PrefAlign, uint32_t TypeByteWidth);
134 //! Internal helper method that returns requested alignment for type.
135 unsigned getAlignment(Type *Ty, bool abi_or_pref) const;
137 /// Valid alignment predicate.
139 /// Predicate that tests a LayoutAlignElem reference returned by get() against
140 /// InvalidAlignmentElem.
141 bool validAlignment(const LayoutAlignElem &align) const {
142 return &align != &InvalidAlignmentElem;
145 /// Valid pointer predicate.
147 /// Predicate that tests a PointerAlignElem reference returned by get() against
148 /// InvalidPointerElem.
149 bool validPointer(const PointerAlignElem &align) const {
150 return &align != &InvalidPointerElem;
153 /// Parses a target data specification string. Assert if the string is
155 void parseSpecifier(StringRef LayoutDescription);
160 /// @note This has to exist, because this is a pass, but it should never be
164 /// Constructs a DataLayout from a specification string. See init().
165 explicit DataLayout(StringRef LayoutDescription)
166 : ImmutablePass(ID) {
167 init(LayoutDescription);
170 /// Initialize target data from properties stored in the module.
171 explicit DataLayout(const Module *M);
173 DataLayout(const DataLayout &DL) :
175 LittleEndian(DL.isLittleEndian()),
176 StackNaturalAlign(DL.StackNaturalAlign),
177 LegalIntWidths(DL.LegalIntWidths),
178 Alignments(DL.Alignments),
179 Pointers(DL.Pointers),
183 ~DataLayout(); // Not virtual, do not subclass this class
185 /// DataLayout is an immutable pass, but holds state. This allows the pass
186 /// manager to clear its mutable state.
187 bool doFinalization(Module &M);
189 /// Parse a data layout string (with fallback to default values). Ensure that
190 /// the data layout pass is registered.
191 void init(StringRef LayoutDescription);
193 /// Layout endianness...
194 bool isLittleEndian() const { return LittleEndian; }
195 bool isBigEndian() const { return !LittleEndian; }
197 /// getStringRepresentation - Return the string representation of the
198 /// DataLayout. This representation is in the same format accepted by the
199 /// string constructor above.
200 std::string getStringRepresentation() const;
202 /// isLegalInteger - This function returns true if the specified type is
203 /// known to be a native integer type supported by the CPU. For example,
204 /// i64 is not native on most 32-bit CPUs and i37 is not native on any known
205 /// one. This returns false if the integer width is not legal.
207 /// The width is specified in bits.
209 bool isLegalInteger(unsigned Width) const {
210 for (unsigned i = 0, e = (unsigned)LegalIntWidths.size(); i != e; ++i)
211 if (LegalIntWidths[i] == Width)
216 bool isIllegalInteger(unsigned Width) const {
217 return !isLegalInteger(Width);
220 /// Returns true if the given alignment exceeds the natural stack alignment.
221 bool exceedsNaturalStackAlignment(unsigned Align) const {
222 return (StackNaturalAlign != 0) && (Align > StackNaturalAlign);
225 /// fitsInLegalInteger - This function returns true if the specified type fits
226 /// in a native integer type supported by the CPU. For example, if the CPU
227 /// only supports i32 as a native integer type, then i27 fits in a legal
228 // integer type but i45 does not.
229 bool fitsInLegalInteger(unsigned Width) const {
230 for (unsigned i = 0, e = (unsigned)LegalIntWidths.size(); i != e; ++i)
231 if (Width <= LegalIntWidths[i])
236 /// Layout pointer alignment
237 /// FIXME: The defaults need to be removed once all of
238 /// the backends/clients are updated.
239 unsigned getPointerABIAlignment(unsigned AS = 0) const {
240 DenseMap<unsigned, PointerAlignElem>::const_iterator val = Pointers.find(AS);
241 if (val == Pointers.end()) {
242 val = Pointers.find(0);
244 return val->second.ABIAlign;
247 /// Return target's alignment for stack-based pointers
248 /// FIXME: The defaults need to be removed once all of
249 /// the backends/clients are updated.
250 unsigned getPointerPrefAlignment(unsigned AS = 0) const {
251 DenseMap<unsigned, PointerAlignElem>::const_iterator val = Pointers.find(AS);
252 if (val == Pointers.end()) {
253 val = Pointers.find(0);
255 return val->second.PrefAlign;
257 /// Layout pointer size
258 /// FIXME: The defaults need to be removed once all of
259 /// the backends/clients are updated.
260 unsigned getPointerSize(unsigned AS = 0) const {
261 DenseMap<unsigned, PointerAlignElem>::const_iterator val = Pointers.find(AS);
262 if (val == Pointers.end()) {
263 val = Pointers.find(0);
265 return val->second.TypeByteWidth;
267 /// Layout pointer size, in bits
268 /// FIXME: The defaults need to be removed once all of
269 /// the backends/clients are updated.
270 unsigned getPointerSizeInBits(unsigned AS = 0) const {
271 return getPointerSize(AS) * 8;
274 /// Layout pointer size, in bits, based on the type. If this function is
275 /// called with a pointer type, then the type size of the pointer is returned.
276 /// If this function is called with a vector of pointers, then the type size
277 /// of the pointer is returned. This should only be called with a pointer or
278 /// vector of pointers.
279 unsigned getPointerTypeSizeInBits(Type *) const;
281 unsigned getPointerTypeSize(Type *Ty) const {
282 return getPointerTypeSizeInBits(Ty) / 8;
287 /// Type SizeInBits StoreSizeInBits AllocSizeInBits[*]
288 /// ---- ---------- --------------- ---------------
297 /// X86_FP80 80 80 96
299 /// [*] The alloc size depends on the alignment, and thus on the target.
300 /// These values are for x86-32 linux.
302 /// getTypeSizeInBits - Return the number of bits necessary to hold the
303 /// specified type. For example, returns 36 for i36 and 80 for x86_fp80.
304 /// The type passed must have a size (Type::isSized() must return true).
305 uint64_t getTypeSizeInBits(Type *Ty) const;
307 /// getTypeStoreSize - Return the maximum number of bytes that may be
308 /// overwritten by storing the specified type. For example, returns 5
309 /// for i36 and 10 for x86_fp80.
310 uint64_t getTypeStoreSize(Type *Ty) const {
311 return (getTypeSizeInBits(Ty)+7)/8;
314 /// getTypeStoreSizeInBits - Return the maximum number of bits that may be
315 /// overwritten by storing the specified type; always a multiple of 8. For
316 /// example, returns 40 for i36 and 80 for x86_fp80.
317 uint64_t getTypeStoreSizeInBits(Type *Ty) const {
318 return 8*getTypeStoreSize(Ty);
321 /// getTypeAllocSize - Return the offset in bytes between successive objects
322 /// of the specified type, including alignment padding. This is the amount
323 /// that alloca reserves for this type. For example, returns 12 or 16 for
324 /// x86_fp80, depending on alignment.
325 uint64_t getTypeAllocSize(Type *Ty) const {
326 // Round up to the next alignment boundary.
327 return RoundUpAlignment(getTypeStoreSize(Ty), getABITypeAlignment(Ty));
330 /// getTypeAllocSizeInBits - Return the offset in bits between successive
331 /// objects of the specified type, including alignment padding; always a
332 /// multiple of 8. This is the amount that alloca reserves for this type.
333 /// For example, returns 96 or 128 for x86_fp80, depending on alignment.
334 uint64_t getTypeAllocSizeInBits(Type *Ty) const {
335 return 8*getTypeAllocSize(Ty);
338 /// getABITypeAlignment - Return the minimum ABI-required alignment for the
340 unsigned getABITypeAlignment(Type *Ty) const;
342 /// getABIIntegerTypeAlignment - Return the minimum ABI-required alignment for
343 /// an integer type of the specified bitwidth.
344 unsigned getABIIntegerTypeAlignment(unsigned BitWidth) const;
346 /// getPrefTypeAlignment - Return the preferred stack/global alignment for
347 /// the specified type. This is always at least as good as the ABI alignment.
348 unsigned getPrefTypeAlignment(Type *Ty) const;
350 /// getPreferredTypeAlignmentShift - Return the preferred alignment for the
351 /// specified type, returned as log2 of the value (a shift amount).
352 unsigned getPreferredTypeAlignmentShift(Type *Ty) const;
354 /// getIntPtrType - Return an integer type with size at least as big as that
355 /// of a pointer in the given address space.
356 IntegerType *getIntPtrType(LLVMContext &C, unsigned AddressSpace = 0) const;
358 /// getIntPtrType - Return an integer (vector of integer) type with size at
359 /// least as big as that of a pointer of the given pointer (vector of pointer)
361 Type *getIntPtrType(Type *) const;
363 /// getSmallestLegalIntType - Return the smallest integer type with size at
364 /// least as big as Width bits.
365 Type *getSmallestLegalIntType(LLVMContext &C, unsigned Width = 0) const;
367 /// getLargestLegalIntType - Return the largest legal integer type, or null if
369 Type *getLargestLegalIntType(LLVMContext &C) const {
370 unsigned LargestSize = getLargestLegalIntTypeSize();
371 return (LargestSize == 0) ? 0 : Type::getIntNTy(C, LargestSize);
374 /// getLargestLegalIntType - Return the size of largest legal integer type
375 /// size, or 0 if none are set.
376 unsigned getLargestLegalIntTypeSize() const;
378 /// getIndexedOffset - return the offset from the beginning of the type for
379 /// the specified indices. This is used to implement getelementptr.
380 uint64_t getIndexedOffset(Type *Ty, ArrayRef<Value *> Indices) const;
382 /// getStructLayout - Return a StructLayout object, indicating the alignment
383 /// of the struct, its size, and the offsets of its fields. Note that this
384 /// information is lazily cached.
385 const StructLayout *getStructLayout(StructType *Ty) const;
387 /// getPreferredAlignment - Return the preferred alignment of the specified
388 /// global. This includes an explicitly requested alignment (if the global
390 unsigned getPreferredAlignment(const GlobalVariable *GV) const;
392 /// getPreferredAlignmentLog - Return the preferred alignment of the
393 /// specified global, returned in log form. This includes an explicitly
394 /// requested alignment (if the global has one).
395 unsigned getPreferredAlignmentLog(const GlobalVariable *GV) const;
397 /// RoundUpAlignment - Round the specified value up to the next alignment
398 /// boundary specified by Alignment. For example, 7 rounded up to an
399 /// alignment boundary of 4 is 8. 8 rounded up to the alignment boundary of 4
400 /// is 8 because it is already aligned.
401 template <typename UIntTy>
402 static UIntTy RoundUpAlignment(UIntTy Val, unsigned Alignment) {
403 assert((Alignment & (Alignment-1)) == 0 && "Alignment must be power of 2!");
404 return (Val + (Alignment-1)) & ~UIntTy(Alignment-1);
407 static char ID; // Pass identification, replacement for typeid
410 /// StructLayout - used to lazily calculate structure layout information for a
411 /// target machine, based on the DataLayout structure.
415 unsigned StructAlignment;
416 unsigned NumElements;
417 uint64_t MemberOffsets[1]; // variable sized array!
420 uint64_t getSizeInBytes() const {
424 uint64_t getSizeInBits() const {
428 unsigned getAlignment() const {
429 return StructAlignment;
432 /// getElementContainingOffset - Given a valid byte offset into the structure,
433 /// return the structure index that contains it.
435 unsigned getElementContainingOffset(uint64_t Offset) const;
437 uint64_t getElementOffset(unsigned Idx) const {
438 assert(Idx < NumElements && "Invalid element idx!");
439 return MemberOffsets[Idx];
442 uint64_t getElementOffsetInBits(unsigned Idx) const {
443 return getElementOffset(Idx)*8;
447 friend class DataLayout; // Only DataLayout can create this class
448 StructLayout(StructType *ST, const DataLayout &DL);
452 // The implementation of this method is provided inline as it is particularly
453 // well suited to constant folding when called on a specific Type subclass.
454 inline uint64_t DataLayout::getTypeSizeInBits(Type *Ty) const {
455 assert(Ty->isSized() && "Cannot getTypeInfo() on a type that is unsized!");
456 switch (Ty->getTypeID()) {
457 case Type::LabelTyID:
458 return getPointerSizeInBits(0);
459 case Type::PointerTyID:
460 return getPointerSizeInBits(Ty->getPointerAddressSpace());
461 case Type::ArrayTyID: {
462 ArrayType *ATy = cast<ArrayType>(Ty);
463 return ATy->getNumElements() *
464 getTypeAllocSizeInBits(ATy->getElementType());
466 case Type::StructTyID:
467 // Get the layout annotation... which is lazily created on demand.
468 return getStructLayout(cast<StructType>(Ty))->getSizeInBits();
469 case Type::IntegerTyID:
470 return Ty->getIntegerBitWidth();
473 case Type::FloatTyID:
475 case Type::DoubleTyID:
476 case Type::X86_MMXTyID:
478 case Type::PPC_FP128TyID:
479 case Type::FP128TyID:
481 // In memory objects this is always aligned to a higher boundary, but
482 // only 80 bits contain information.
483 case Type::X86_FP80TyID:
485 case Type::VectorTyID: {
486 VectorType *VTy = cast<VectorType>(Ty);
487 return VTy->getNumElements() * getTypeSizeInBits(VTy->getElementType());
490 llvm_unreachable("DataLayout::getTypeSizeInBits(): Unsupported type");
494 } // End llvm namespace